1. Field of the Invention
The present invention relates to an infrared communication system and a remote control apparatus that use an infrared signal, in particular, to an infrared communication system and an infrared signal receiving apparatus that can be suitably used near a plasma display panel.
2. Description of the Related Art
When an electronic device such as audio-visual (AV) device, an air conditioner, and so forth are remotely controlled, infrared signals are used. For example, a remote control commander (hereinafter referred to as a remote controller) modulates a signal corresponding to a key input in a predetermined manner. A light emitting diode (LED) or the like of the remote commander converts the electric signal into an infrared signal. Thereafter, the remote controller transmits the infrared signal. In the reception side, a light reception device such as a photo diode receives the infrared signal and converts it into an electric signal. Thereafter, the reception side demodulates the received signal in a predetermined manner and obtains the control signal corresponding to the key input of the remote controller.
The infrared signals are also used to transmit not only signals of the remote controller, but also audio signals, image signals, and picture signals. For example, a headset system that wirelessly transmits an audio signal using an infrared signal has been practically used. A wireless microphone for a Karaoke device may use an infrared signal to wirelessly transmit an audio signal. In addition, when other electronic devices are remotely controlled, infrared signals may be used to perform television conversation and control small video cameras for security facilities.
In a regular remote controller, the transmission section uses an infrared signal whose peak is around 940 nm and the reception signal uses an infrared signal whose peak is around 875 nm to prevent them from mutually interfering.
In recent years, television receivers that have a large display screen and a thin housing have been desired. As products that satisfy them, television receivers that use a plasma display panel (hereinafter abbreviated as PDP) as a display device have been noticeably outspread. The PDP theoretically has two glass substrates on which transparent electrodes are formed and that are closely disposed. Inert gas such as argon or neon is filled in the glass substrates. By applying a high voltage to the inert gas, a plasma discharge takes place. The plasma discharge causes the inert gas to emit ultraviolet rays. By emitting the ultraviolet rays to predetermined phosphors, colors of red (R), green (G), and blue (B) are produced as full colors. The following non-patent document 1 describes an example of a television receiver that uses the PDP as a display device.    [Non-patent document 1] “FPD (Flat Panel Display) aiming at Television (translated title),” Nikkei Electronics Special Issue, Nikkei BP Corp., Oct. 25, 1999, pp. 93-104, Masaharu Tanaka, et. al.